De Development of of MASH Co Computer Sim imulated Steel Bri - - PowerPoint PPT Presentation

De Development of

• f MASH Co

Computer Sim imulated Steel Bri Bridge Rail il and Transition De Details

Chuck A. Plaxico, Ph.D.

Roadsafe LLC

NETC Webinar July 16, 2020

Project: NETC 18-1

Background and Project Motivation

• The current policy for roadside hardware

installed on federal-aid projects requires upgrading non-conforming systems to MASH acceptance level for situations involving full system replacements, certain structural rehabilitations (e.g., deck replacements), or repairing a critically damaged bridge rail system.

• The predominate bridge rail and approach

guardrail transition (AGT) systems used in the New England states, include details for 2-bar, 3- bar and 4-bar designs, which were developed and tested under prior crash testing and evaluation standards.

• It was of interest to the New England

Transportation Agencies to determine if these existing NETC designs meet the strength and safety criteria of the current test standard (i.e., MASH), which involve higher impact severities than the previous crash testing standards.

Slide 3

Objectives

• Review of NETC style bridge rail and

AGT designs to:

1) Determine preliminary MASH compliance/equivalency:

• AASHTO LRFD Bridge Design Specifications
• Procedures outlined in NCHRP Project 20-07

(395)

2) Determine the least conservative designs for further evaluation using FEA crash simulation.

• Evaluate the crash performance of

these systems using finite element analysis (FEA) computer simulation using MASH test conditions and criteria:

• Structural capacity
• Risk of occupant injury
• Vehicle stability

NETC Bridge Rails

Three design details were evaluated:

• 1. NETC curb-mounted 2-Bar Rail (TL3)
• 2. NETC curb-mounted 3-Bar Rail (TL4)
• 3. NETC sidewalk-mounted 4-Bar Rail (TL4)

Slight variations in design details depending

• n State

NETC Bridge Rails

W6x25 8’ (spacing) 7”or 9” 12”x10”x1” Baseplate Four 1” Dia. A449 Anchor Bolts ¾” Dia. A325 Rail Splice 1.5’ HSS 4 x 4 x ¼ HSS 8 x 4 x 5/16

NETC Bridge Rails

9.5” 7” 11.5” 12”

42” 41.5”

7”

44”

12” 12” 11”

NETC 3-Bar BR

6” 7”

34”

12” 11”

NETC 2-Bar BR

6” Integral concrete curb Integral concrete curb Sidewalk

Slide 8

NETC Bridge Rails

5/8”-Diameter A307 Cap Screws Washer and Bushing/Spacer Washer Only

(bolt tension = 20 kip)

¾” ¼” internal gap (each side) Tested Design ¾” longitudinal gap

Slide 10

20 40 60 80 100 120 140 160 180

Report 350 (TL-4) AASHTO '98 (PL-2) MASH (TL-4) Impact Severity (kip-ft) Test Procedure small car test pick-up test SUT test

830C 2000P 8000S 1100C 2270P 10000S

Comparing Impact Severity

(Report 350 and MASH)

Test Vehicles

Report 350 MASH

22 kip 56 mph 15 deg. 18 kip 50 mph 15 deg. 2.4 kip 62 mph 25 deg. 1.8 kip 62 mph 20 deg. 5.0 kip 62 mph 25 deg. 4.4 kip 62 mph 25 deg. 54%

1100C 2270P 10000S 830C 2000P 8000S

14% > mass 22% > mass 33% > mass 25% > angle 12% > speed

MASH Equivalency Assessment

LRFD Assessments

Rail Height Rail Geometrics Strength Rail Height Rail Geometrics Strength Rail Height Rail Geometrics Strength Required 29 71 k 36 in 80 k 36 in 80 k Actual 34 109 k 42 in 83-86 k 42 in 76-81 k* Assessment S S S(1) S S(2) S S M NS / S

NS - Not Satisfactory M - Marginal S - Satisfactory S

(1) - Satisfactory Rating for TL-3 Only

S

(2) - Satisfactory when 9" curb is used

* - Differs from 20-07(395) report (see Table 5) (see Table 5) (see Table 5)

NETC 2-Bar (TL3) NETC 3-Bar (TL4) NETC 4-Bar (TL4) S – 9” curb M – 7” curb

• Rail geometrics are used to assess potential for vehicle

snag on posts and considers:

• post-offset distance
• Max vertical clear opening between rails
• Contact surface w.r.t. overall barrier height

Slide 12

Research Approach for FEA Crash Simulations

• Develop finite element models of existing

hardware.

• Validate the models using the procedures
• utlined in NCHRP Web Document 179 by

comparing results to existing full-scale crash tests on the system.

• Update models to include MASH vehicle

types and impact conditions

• Then use FEA to simulate MASH tests and

evaluate the system’s performance.

Slide 13

NETC 4-Bar

Validation

• Test No. NETC-3 on the bridge rail was

performed by SwRI on 12/18/1997.

• Total length of bridge rail was 108 feet.
• Impact conditions:
• Mass = 17,875 lb (8,108 kg)
• Speed = 49.8 mph (80.1 km/hr)
• Angle = 15 deg.
• Impact point = 2 ft (0.61 m) upstream of Post 6.

System Type: Comparison: Device Name:/Variant: Submissions Type: Non-Significant -- Effect is Uncertain Testing Criterion: Non-Significant -- Effect is Positive Test Level: Non-Significant -- Effect is Inconsequential FHWA Letter: X Baseline Validation of Crash Test to FEA Analysis.

Crash Test FEA Analysis

Test Number: Test FEA Occupant Risk (cont.) Test FEA Vehicle: yes yes H2 – Long. OIV 5.4 ft/s 5.9 ft/s Vehicle Mass: 0.51 in 0.7 in H3 – Lat. OIV 9.5 ft/s 12.1 ft/s Impact Speed:

• 42 ft

I2 – Long. ORA 8.95 g 4.95 g Impact Location: no no I3 – Lat. ORA 14.3 g 12.1 g Tested Hardware: Original Design no no Vehicle Trajectory FEA Hardware: Original Design no no K – Intruded into travel lanes? no no no no N – Travel behind barrier? no no Total Energy: 0% Pass Test FEA Hourglass Energy: 0% Pass no no Sprague-Geer Magnitude < 40

• Mass Added:

0% Pass 20 14.7 Sprague-Geer Phase < 40

• Shooting Nodes:

no Pass 5 5.4 ANOVA Mean

• Negative Volumes:

no Pass 14.8 16.2 ANOVA Standard Deviation

• F2 – Max. Vehicle Roll

F3 – Max. Vehicle Pitch F4 – Max. Vehicle Yaw Crash tested original design to FEA of original design A5 – Barrier Rupture? A7 – Wheel Snagging? A8 – Vehicle Snagging? Occupant Risk D – Detached elements? Structural Adequacy A1 - Acceptable perf.? A2 – Permanent Deflection: A3 – Contact Length A4 - Component Failure Baseline Crash Test W-179 Table E-1: Verification Evaluation Summary W-179 Table E-3 (Multi-Channel Method) W-179 Table E-5: Roadside PIRTS Summary of FEA vs. Test Validation Metrics SwRI NETC-3 1993 International 4600 LP 17,875 lbs 49.8 mph 2 ft upstream of Post 6 Bridge Rail NETC 4-Bar sidewalk-mounted Report 350 TL4

Time = 0.0 sec 0.2 sec 0.4 sec 0.6 sec 0.9 sec 1.2 sec

NETC 4-Bar

Validation

MASH TL-3 for NETC 2-Bar Bridge Rail

Test 3-10

• Impact Speed = 62.1 mph
• Impact Angle = 25 degrees
• Impact Point = 3.6 ft upstream

from critical Post

Test 3-11

• Impact Speed = 62.1 mph
• Impact Angle = 25 degrees
• Impact Point = 4.3 ft upstream

from critical Post

Slide 16

Lateral Dynamic Deflection

Maximum dynamic deflection = 3.6 in (92 mm) Maximum dynamic deflection = 2.7 in (69 mm)

(mm)

Test 3-10 Test 3-11

(mm)

Slide 17

Assessment of Potential Vehicle Contact with Post

• The front fender made slight contact with the post.
• The contact between the front tire and post was

moderate.

• Tire deflation was not included in the model, so an accurate

assessment on the potential for wheel rim snag on the post could not be made; however, a moderate snag is possible.

Slide 18

5 10 15 20 25 30 35 40 OIV-x OIV-y THIV

OIV (ft/s)

OIV

Test 3-10 2 4 6 8 10 12 14 16 18 20 ORA-x ORA-y PHD

ORA (G)

ORA

Test 3-10

• 35
• 30
• 25
• 20
• 15
• 10
• 5

5 10 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Y-acceleration (G's) Time (seconds)

y-acc (10-ms Avg.)

Test 3-10 Time of OIV

• 30
• 25
• 20
• 15
• 10
• 5

5 10 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 X-acceleration (G's) Time (seconds)

x-acc (10-ms Avg.)

Test 3-10 Time of OIV

Occupant Risk Test 3-10

Occupant Impact Velocity Occupant Ridedown Accelerations

Max Criteria Preferred Limit Max Criteria Preferred Limit

Slide 19

Assessment of Potential Vehicle Snag

• The front fender and bumper made slight contact

with the post, but the contact force was negligible.

• The front wheel and the front edge of the

passenger door snagged on the rail tube at the splice but resulting accelerations did not exceed

• ccupant risk criteria.

Front Wheel Snag Door Snag

Slide 20

5 10 15 20 25 30 35 40 OIV-x OIV-y THIV

OIV (ft/s)

OIV

Test 3-11 2 4 6 8 10 12 14 16 18 20 ORA-x ORA-y PHD

ORA (G)

ORA

Test 3-11

• 20
• 15
• 10
• 5

5 10 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Y-acceleration (G's) Time (seconds)

y-acc (10-ms Avg.)

Test 3-11 Time of OIV

• 20
• 15
• 10
• 5

5 10 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 X-acceleration (G's) Time (seconds)

x-acc (10-ms Avg.)

Test 3-11 Time of OIV

Occupant Risk Test 3-11

20 Max Criteria Preferred Limit Max Criteria Preferred Limit

Occupant Impact Velocity Occupant Ridedown Accelerations

Slide 23

Conclusions for the NETC 2-BAR Bridge Rail

Evaluation Factors Evaluation Criteria Results Structural Adequacy A Test article should contain and redirect the vehicle or bring the vehicle to a controlled stop; the vehicle should not penetrate, underride, or override the installation although controlled lateral deflection of the test article is acceptable. Pass Occupant Risk D Detached elements, fragments, or other debris from the test article should not penetrate or show potential for penetrating the occupant compartment, or present undue hazard to other traffic, pedestrians, or personnel in a work zone. Deformations

• f, or intrusions into, to occupant compartment should not

exceed limits set forth in Section 5.2.2 and Appendix E. Pass F The vehicle should remain upright during and after collision. The maximum roll and pitch angles are not to exceed 75 degrees. Pass H The longitudinal and lateral occupant impact velocity (OIV) shall not exceed 40 ft/s (12.2 m/s), with a preferred limit of 30 ft/s (9.1 m/s) Pass I The longitudinal and lateral occupant ridedown acceleration (ORA) shall not exceed 20.49 G, with a preferred limit of 15.0 G Pass

MASH TL-4 for NETC 3-Bar Bridge Rail

Test 4-10

• Impact Speed = 62.1 mph
• Impact Angle = 25 degrees
• Impact Point = 3.6 ft upstream

from critical Post

Test 4-11

• Impact Speed = 62.1 mph
• Impact Angle = 25 degrees
• Impact Point = 4.3 ft upstream

from critical Post

Slide 25

Lateral Dynamic Deflection

Maximum dynamic deflection = 3.35 in (85 mm) Maximum dynamic deflection = 4.2 in (106 mm)

(mm)

Test 4-10 Test 4-11

Slide 26

Movies

Slide 27

Assessment of Potential Vehicle Snag

• The tire rim snagged on the splice
• Tires did not contact post.

Slide 28

Occupant Risk

5 10 15 20 25 30 35 40 OIV-x OIV-y THIV

OIV (ft/s)

OIV

Test 4-10 2 4 6 8 10 12 14 16 18 20 ORA-x ORA-y PHD

ORA (G)

ORA

Test 4-10

Occupant Impact Velocity Occupant Ridedown Accelerations

Max Criteria Preferred Limit Max Criteria Preferred Limit

Test 4-10 Test 4-10

5 10 15 20 25 30 35 40 OIV-x OIV-y THIV

OIV (ft/s)

OIV

Test 4-11 2 4 6 8 10 12 14 16 18 20 ORA-x ORA-y PHD

ORA (G)

ORA

Test 4-11

Max Criteria Preferred Limit Max Criteria Preferred Limit

Test 4-11 Test 4-11

Slide 31

Conclusions on Test 4-10 and 4-11 on the NETC 3-Bar

Evaluation Factors Evaluation Criteria Results Structural Adequacy A Test article should contain and redirect the vehicle or bring the vehicle to a controlled stop; the vehicle should not penetrate, underride, or override the installation although controlled lateral deflection of the test article is acceptable. Pass Occupant Risk D Detached elements, fragments, or other debris from the test article should not penetrate or show potential for penetrating the occupant compartment, or present undue hazard to other traffic, pedestrians, or personnel in a work zone. Deformations

• f, or intrusions into, to occupant compartment should not

exceed limits set forth in Section 5.2.2 and Appendix E. Pass F The vehicle should remain upright during and after collision. The maximum roll and pitch angles are not to exceed 75 degrees. Pass H The longitudinal and lateral occupant impact velocity (OIV) shall not exceed 40 ft/s (12.2 m/s), with a preferred limit of 30 ft/s (9.1 m/s) Pass I The longitudinal and lateral occupant ridedown acceleration (ORA) shall not exceed 20.49 G, with a preferred limit of 15.0 G Pass

Test 4-12 (Case 1)

• Impact Speed = 56 mph
• Impact Angle = 15 degrees
• Impact Point = 5.0 ft upstream from critical

Post

• Bed Height = 47.5” (e.g., Ford F800)

Test 4-12 (Case 2)

• Impact Speed = 56 mph
• Impact Angle = 15 degrees
• Impact Point = 5.0 ft upstream from

critical Post

• Bed Height = 50” (e.g., GMC)

MASH Test 4-12 for NETC 3-Bar Bridge Rail

Slide 33

Bed Height = 47.5 inches Bed Height = 50 inches

Slide 34

Lateral Dynamic Deflection

Maximum dynamic deflection = 7.64 in (194 mm) Case 1 (47.5”)

(mm)

Case 2 (50”) Maximum dynamic deflection

• Lateral = 8.1 in (207 mm)
• Vertical = 1.3 in (33 mm)

7 8 9 6 5 7 8 9 6 5

Slide 35

Conclusions on Test 4-12 on the NETC 3-Bar

Evaluation Factors Evaluation Criteria – MASH Test 4-12 Results Case 1/ Case 2 Structural Adequacy A Test article should contain and redirect the vehicle or bring the vehicle to a controlled stop; the vehicle should not penetrate, underride, or override the installation although controlled lateral deflection of the test article is acceptable. Pass/Pass Occupant Risk D Detached elements, fragments, or other debris from the test article should not penetrate or show potential for penetrating the occupant compartment, or present undue hazard to other traffic, pedestrians, or personnel in a work zone. Deformations of, or intrusions into, to

• ccupant compartment should not exceed limits set forth

in Section 5.2.2 and Appendix E. Pass/Pass G It is preferable, although not essential, that the vehicle remain upright during and after collision. Pass/Fail

MASH TL-4 for NETC 4-Bar Bridge Rail

Test 4-10

• Impact Speed = 62.1 mph
• Impact Angle = 25 degrees
• Impact Point = 3.6 ft upstream

from critical Post

Test 4-11

• Impact Speed = 62.1 mph
• Impact Angle = 25 degrees
• Impact Point = 4.3 ft upstream

from critical Post

Slide 37

Assessment of Potential Vehicle Snag

• The top of the front fender made slight

contact with the post, but the contact force was negligible.

• The tire rim snagged on the splice at the

lower-middle tube rail, which resulted in peak longitudinal acceleration of 21.6 G and Peak lateral acceleration of 25.8 G.

• Tires did not contact post.

5 10 15 20 25 30 35 40 OIV-x OIV-y THIV

OIV (ft/s)

OIV

NETC 4-Bar 2 4 6 8 10 12 14 16 18 20 ORA-x ORA-y PHD

ORA (G)

ORA

NETC 4-Bar

• 25
• 20
• 15
• 10
• 5

5 10 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 X-acceleration (G's) Time (seconds)

x-acc (10-ms Avg.)

NETC 4-Bar Time of OIV

• 30
• 25
• 20
• 15
• 10
• 5

5 10 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Y-acceleration (G's) Time (seconds)

y-acc (10-ms Avg.)

NETC 4-Bar Time of OIV

Occupant Risk Test 4-20

Occupant Impact Velocity Occupant Ridedown Accelerations

Max Criteria Preferred Limit Max Criteria Preferred Limit Front wheel snag at splice Front wheel snag at splice

Slide 39

Assessment of Potential Vehicle Snag

• The front fender and bumper made slight

contact with the post, but the contact force was negligible.

• The rear wheel tire and rim snagged on the

rail tube at the splice, resulting in maximum ORA.

Front of Vehicle Rear Tire

5 10 15 20 25 30 35 40 OIV-x OIV-y THIV

OIV (ft/s)

OIV

Test 4-11 2 4 6 8 10 12 14 16 18 20 ORA-x ORA-y PHD

ORA (G)

ORA

Test 4-11

• 20
• 15
• 10
• 5

5 10 15 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 X-acceleration (G's) Time (seconds)

x-acc (10-ms Avg.)

Test 4-11 Time of OIV

• 20
• 15
• 10
• 5

5 10 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Y-acceleration (G's) Time (seconds)

y-acc (10-ms Avg.)

Test 4-11 Time of OIV

Occupant Risk Test 4-21

40 Max Criteria Preferred Limit Max Criteria Preferred Limit

Occupant Impact Velocity Occupant Ridedown Accelerations

Rear wheel snag at splice Rear tail-slap Model tends to

• ver-predict

accelerations for tail-slap

Slide 41

Lateral Dynamic Deflection

Maximum dynamic deflection = 2.8 in (72 mm) Maximum dynamic deflection = 5.4 in (138 mm)

Test 4-10 Test 4-11

(mm) (mm)

Slide 42

Conclusions for Test 4-10 and 4-11 on the NETC 4-BAR

Evaluation Factors Evaluation Criteria Results Structural Adequacy A Test article should contain and redirect the vehicle or bring the vehicle to a controlled stop; the vehicle should not penetrate, underride, or override the installation although controlled lateral deflection of the test article is acceptable. Pass Occupant Risk D Detached elements, fragments, or other debris from the test article should not penetrate or show potential for penetrating the occupant compartment, or present undue hazard to other traffic, pedestrians, or personnel in a work zone. Deformations

• f, or intrusions into, to occupant compartment should not

exceed limits set forth in Section 5.2.2 and Appendix E. Pass F The vehicle should remain upright during and after collision. The maximum roll and pitch angles are not to exceed 75 degrees. Pass H The longitudinal and lateral occupant impact velocity (OIV) shall not exceed 40 ft/s (12.2 m/s), with a preferred limit of 30 ft/s (9.1 m/s) Pass I The longitudinal and lateral occupant ridedown acceleration (ORA) shall not exceed 20.49 G, with a preferred limit of 15.0 G Pass

Slide 43

MASH Tes est 4-12 Sim imulatio ion

• Impact Conditions
• Mass = 22,061 lb
• Impact Speed = 56 mph (90 km/hr)
• Impact Angle = 15 degrees
• Target Impact Point = 5.0 ft upstream of

Post 7

Slide 44

Lateral Dynamic Deflection

Maximum dynamic deflection = 8.15 in (207 mm)

(mm)

Barrier Damage

• Analysis indicated probable crack opening

in concrete at front anchor bolts at maximum dynamic deflection.

• Max dynamic 1st Prin. Strain = 0.079
• Final 1st Prin. Strain = 0.054

Dynamic at time = 0.515 seconds Final Static

Crack Opening Significant Crack Opening

Slide 46

Conclusions on Test 4-12 on the NETC 4-Bar

Evaluation Factors Evaluation Criteria – MASH Test 4-12 Results Structural Adequacy A Test article should contain and redirect the vehicle or bring the vehicle to a controlled stop; the vehicle should not penetrate, underride, or override the installation although controlled lateral deflection of the test article is acceptable. Pass Occupant Risk D Detached elements, fragments, or other debris from the test article should not penetrate or show potential for penetrating the occupant compartment, or present undue hazard to other traffic, pedestrians, or personnel in a work zone. Deformations of, or intrusions into, to

• ccupant compartment should not exceed limits set forth

in Section 5.2.2 and Appendix E. Pass G It is preferable, although not essential, that the vehicle remain upright during and after collision. Pass

Slide 47

Sum ummary ry for NETC Bridge Rail Designs

• NETC 2-Bar:
• Meets MASH TL3 criteria with only moderate barrier damages.
• Concrete curb damage was likely for Test 3-11.
• NETC 3-Bar and 4-Bar:
• The barrier system meets MASH TL4 criteria; however, relatively high barrier

damages are likely under these conditions.

Slide 48

NETC Transition Systems

• Three design options were evaluated:
• 1. NETC Style 2-Bar Rail and Thrie Beam

(TL3) (NHDOT steel rail transition)

• 2. NETC Style 3-Bar Rail and Thrie Beam

(TL4) (NHDOT steel rail transition)

• 3. Concrete Transition Barrier and Thrie

Beam (TL4) (MaineDOT standard detail)

• Single taper on top
• No face taper

Slide 49

NETC 2-Bar Transition

The transition system for the 2-Bar bridge rail was modeled based on the detailed drawing from NHDOT

Tube Rail Transition (2 layers) 12 ga. thrie beam 10 ga. End-shoe 3/8” thick connector plate 3/8” thick deflector plate 12 ga. W-beam Guardrail NETC 2-Bar BR

W6x25 Posts (typ.) 8’ long W6x9 Posts (typ.) 7’ long

Slide 50

NETC 2-Bar to Thrie-Beam AGT

Report 350 Test Level 3

< 15 G < 75° < 30 ft/s

Preferred Limits

401181-1

Test Designation Test 3-21 Test Vehicle 2000 Chevrolet 2500 Gross Vehicle Weight (lb) 4,706 Impact Speed (mph) 63.6 Impact Angle (deg) 24.9 Exit Speed (mph) 52.9 Exit Angle (deg) 11.7 Occupant Impact Velocity Longitudinal (ft/s) 17.1 Lateral (ft/s) 24.6 Ridedown Accel Longitudinal (g's) 8.3 Lateral (g's) 10 Maximum 50 msec Avg Accel Longitudinal (g's) 8.1 Lateral (g's) 13.5 Max Deflection (in) 7.87 Vehicle Trajectory Maximum YawAngle (deg) 56 Maximum Roll Angle (deg) 14 Maximum Pitch Angle (deg) 19 NCHRP Report 350 Evaluation Structural Adequacy Pass Ocupant Risk Pass Vehicle Trajectory Pass

Slide 51

NETC 2-Bar to Thrie-Beam AGT

Validation

FEA (0 - 1.0 seconds) (0 - 1.0 seconds) % Absolute Criteria Pass Occupant Impact Velocity x-direction 17.06 19.68 15.4% 2.62 <20% or < 6.6 f/s Y (ft/s) y-direction

• 24.61
• 24.93

1.3%

• 0.33

<20% or < 6.6 f/s Y at time

at 0.0948 seconds on left side of interior at 0.1005 seconds on left side of interior

29.9 31.5 5.5% 1.64 <20% or < 6.6 f/s Y

at 0.0948 seconds on left side of interior at 0.0986 seconds on left side of interior

Ridedown Acceleration

• 8.3
• 8.3

0.0% 0.00 <20% or < 4G Y (g's)

(0.1153 - 0.1253 seconds) (0.1018 - 0.1118 seconds)

10 7.5 25.0%

• 2.50

<20% or < 4G Y

(0.1182 - 0.1282 seconds) (0.1388 - 0.1488 seconds)

11.9 9.1 23.5%

• 2.80

<20% or < 4G Y

(0.1180 - 0.1280 seconds) (0.1344 - 0.1444 seconds)

1.74 1.48 14.9%

• 0.26

<20% or < 0.2 Y

(0.0216 - 0.0716 seconds) (0.0355 - 0.0855 seconds)

Max 50-ms moving avg. acc.

• 8.1
• 9.6

18.5%

• 1.50

<20% or < 4G Y (g's)

(0.0334 - 0.0834 seconds) (0.0342 - 0.0842 seconds)

13.5 11 18.5%

• 2.50

<20% or < 4G Y

(0.0216 - 0.0716 seconds) (0.0448 - 0.0948 seconds)

• 7.6
• 3.8

50.0% 3.80 <20% or < 4G Y

(0.0209 - 0.0709 seconds) (0.0359 - 0.0859 seconds)

55.6 48.2 13.3%

• 7.40

<20% or < 5 deg Y

(1.0000 seconds) (0.9426 seconds)

• 19.4
• 17

12.4% 2.40 <20% or < 5 deg Y

(0.5914 seconds) (0.4713 seconds)

• 13.7
• 16.5

20.4%

• 2.80

<20% or < 5 deg Y

(0.6647 seconds) (0.5674 seconds)

Maximum Angular Disp. (deg) Roll Yaw THIV (m/s) x-direction y-direction PHD (g's) ASI x-direction y-direction Pitch Error W179 Criteria MASH Test 3-11 Occupant Risk Factors z-direction Test 401181-1

Slide 53

MASH TL-4 for NETC 2-Bar Transition

Test 4-20

• Impact Speed = 62.1 mph
• Impact Angle = 25 degrees
• Impact Point = 6.5 ft upstream

from critical Post

Test 4-21

• Impact Speed = 62.1 mph
• Impact Angle = 25 degrees
• Impact Point = 9 ft upstream

from end of tube rail

Slide 54

MASH TL-4 for NETC 3-Bar Transition

Test 4-20

• Impact Speed = 62.1 mph
• Impact Angle = 25 degrees
• Impact Point = 5.5 ft upstream

from critical Post

Test 4-21

• Impact Speed = 62.1 mph
• Impact Angle = 25 degrees
• Impact Point = 6.2 ft upstream

from end of tube rail

Slide 55

MASH TL-4 for NETC 3-Bar Transition

Test 4-20

• Impact Speed = 62.1 mph
• Impact Angle = 25 degrees
• Impact Point = 5.5 ft upstream

from critical Post

Test 4-21

• Impact Speed = 62.1 mph
• Impact Angle = 25 degrees
• Impact Point = 6.2 ft upstream

from end of tube rail

Slide 56

Conclusions on Tests 3-20 and 3-21

• n 2-Bar and 3-Bar Transition

Evaluation Factors Evaluation Criteria Results Structural Adequacy A Test article should contain and redirect the vehicle or bring the vehicle to a controlled stop; the vehicle should not penetrate, underride, or override the installation although controlled lateral deflection of the test article is acceptable. Pass Occupant Risk D Detached elements, fragments, or other debris from the test article should not penetrate or show potential for penetrating the occupant compartment, or present undue hazard to other traffic, pedestrians, or personnel in a work zone. Deformations

• f, or intrusions into, to occupant compartment should not

exceed limits set forth in Section 5.2.2 and Appendix E. Pass F The vehicle should remain upright during and after collision. The maximum roll and pitch angles are not to exceed 75 degrees. Pass H The longitudinal and lateral occupant impact velocity (OIV) shall not exceed 40 ft/s (12.2 m/s), with a preferred limit of 30 ft/s (9.1 m/s) Pass I The longitudinal and lateral occupant ridedown acceleration (ORA) shall not exceed 20.49 G, with a preferred limit of 15.0 G Pass

Slide 57

MASH Tes est 4-22 Sim imulatio ion

Ford 800 Surrogate

47.5”

9 ft

Critical snag point

• Impact Conditions
• Mass = 22,061 lb
• Impact Speed = 56 mph (90 km/hr)
• Impact Angle = 15 degrees
• Impact Point = 9 ft upstream of Bridge

Rail tube ends

Slide 58

MASH Tes est 4-22 Sim imulatio ion

• Impact Conditions
• Mass = 22,061 lb
• Impact Speed = 56 mph (90 km/hr)
• Impact Angle = 15 degrees
• Impact Point = 9 ft upstream of Bridge

Rail tube ends

Slide 59

Barrier Damage

• Plastic deformations of the steel

components were primarily to the top

• f Post 1 of the transition and to all

three (3) bridge rail posts.

• There was some plastic deformation of

the transition rail elements.

• The damage to the posts were due to

the bottom of the cargo-box snagging

• n the top of the posts. This caused

torque rotation and longitudinal deformation of the posts.

• The vehicle was in contact with the

barrier from the point of contact until the truck box slid off the end of the bridge rail at 0.55 seconds.

• The maximum working width prior to

exiting the barrier was 3.9 ft resulting from the top of the cargo box extending over the bridge rail.

3.9’

Working width

Slide 60

Baseline Original Design (3 ft) Case 2 – ¾” Splice Gap and Tapered Post (5.5 ft) – ¾” Splice Gap and Original – 2”

Slide 61

Conclusions on Test 4-22 on the 3-Bar Trans

Evaluation Factors Evaluation Criteria – MASH Test 4-12 Results Structural Adequacy A Test article should contain and redirect the vehicle or bring the vehicle to a controlled stop; the vehicle should not penetrate, underride, or override the installation although controlled lateral deflection of the test article is acceptable. Pass Occupant Risk D Detached elements, fragments, or other debris from the test article should not penetrate or show potential for penetrating the occupant compartment, or present undue hazard to other traffic, pedestrians, or personnel in a work zone. Deformations of, or intrusions into, to

• ccupant compartment should not exceed limits set forth

in Section 5.2.2 and Appendix E. Pass G It is preferable, although not essential, that the vehicle remain upright during and after collision. Pass

Slide 62

Overall Project Conclusions

The results of this study showed that for:

• NETC Bridge Rail Designs
• 2-bar curb-mounted system meets MASH TL3
• 3-bar curb-mounted system meets MASH TL4
• 4-bar sidewalk-mounted system meets MASH TL4
• However, the 3-bar and 4-bar design resulted in

considerable damage to the system, particularly in the SUT test.

• NETC AGT Designs
• 2-bar to thrie-beam AGT meets MASH TL3
• 3-bar to thrie-beam AGT meets MASH TL4
• The concrete buttress to thrie-beam did not meet

MASH requirements due to snag and high decelerations for small car test

Slide 63

Overall Project Conclusions

• Redesign of the bridge rail system was not a

focus of this study; however, general recommendations were provided to further improve crash performance, including:

• Revising the splice design to minimize

lateral movement in the splice connections.

• Increasing the size of the HSS rails to

improve geometric attributes and strength.

• Tapering the tops of the posts to mitigate

snagging on the top of the posts when parts

• f a vehicle (e.g., cargo-box on single-unit

trucks) overhang the top rail.

• Final Report is posted on the NETC website at:

https://www.newenglandtransportationconso rtium.org/research/netc-research- projects/netc-18-1/

• Max. Disp.

OIVx OIVy ORAx ORAy Roll Pitch (mph) (deg) ft (in) Location (in) (ft/s) (ft/s) (g) (g) (deg) (deg) Test 3-10 62 25 3.6 Pass 3.6 Wheel Well/ Toe Pan 3.3 26.2 33.1 5.5(1) 6.4 7 5.4 Pass Test 3-11 62 25 4.3 Pass 2.7 Wheel Well/ Toe Pan 2.8 20.7 26.9 4.6 15.4(2) 9 10.1 Pass Test 4-10 62 25 3.6 Pass 3.4 Wheel Well/ Toe Pan 2.8 25.6 32.5 6.7(1) 6 7.3 5.2 Pass Test 4-11 62 25 4.3 Pass 4.2 Wheel Well/ Toe Pan 3.3 22 26.6 4.7 15.4(2) 9.9 7.5 Pass Test 4-12(3) 56 15 5 Pass 7.6 Wheel Well/ Toe Pan 1 2 14.8 7 5.3 20.8 7.8 Pass Test 4-12(4) 56 15 5 Pass 8.1 Wheel Well / lower edge of door 3.3 3 14.1 5.7 5.9 90* 6.9 Pass

Mod 3-Bar†

Test 4-10 62 25 3.6 Pass 2.3

• 24.3

32.5 3.5(1) 7.7

• Pass

Test 4-10 62 25 3.6 Pass 2.8 Wheel Well/ Toe Pan 3.4 24 31.5 7.1(1) 10.3 10.9 6.5 Pass Test 4-11 62 25 4.3 Pass 5.4 Wheel Well/ Toe Pan 2.2 17.7 26.6 13.8 18(2) 7.2 8.3 Pass Test 4-12(3) 56 15 5 Pass 8.2 Wheel Well/ Toe Pan 1 3.9 16.7 4.3 6.7 18.8 5.6 Pass

Mod 4-Bar‡

Test 4-12(3) 56 15 5 Pass 8.2 Not Evaluated 1 3.9 16.7 4.3 6.7 18.8 5.6 Pass Test 3-20 62 25 6.5 Pass 6.3 Wheel weel / Toe Pan 1.4 25.3 28.2 7.9(1) 4.8 6.7 3.6 Pass Test 3-21 62 25 9 Pass 11.8 negligible

• 17.4

23.3 4.8 17.2(2) 9.3 5.5 Pass Test 4-20 62 25 5.5 Pass 5.8 Wheel Well/ Toe Pan 1 24.3 25.9 4.2(1) 7.4 6.2 3.9 Pass Test 4-21 62 25 5.5 Pass 8 negligible

• 17.7

24.6 5.2 15.1(2) 8.1 3.7 Pass Test 4-22 56 15 9 Pass 7.6 Wheel Well/ Toe Pan 1 2.3 14.8 8.9 5.5 90* 11.9 Pass** Test 4-20 62 25 5.5 Pass 6.9 Wheel Well/ Toe Pan 3.4 29.2 32.8 26 7.9(2) 5.4 6.8 Fail Test 4-21 62 25 6.5 Pass 8.3 Wheel Well/ Toe Pan 1 21 28.2 9.4 17.3 15.4 9.6 Pass Test 4-22 56 15 12 Pass 17.0 Wheel Well/ Toe Pan 5.5 8.9 14.4 13.9 8.7 8.7 12 Pass*** Test 4-20§ 62 25 4 Pass 3.25

• 25.3

33.1 4.9 2.9(2)

• Pass

Test 4-20§§ 62 25 4 Pass 2.65

• 23.6

32.8 3.7 7.9(2) 4.4 5.1 Pass Test 4-21§ 62 25 6 Pass

• 22.6

27.9 5.8 ≈18-19

• Pass

Test 4-22Ⱡ 56 15 9 Pass 5.4

• Pass**

* The vehicle was still upright when the analysis was terminated, but 90-degree roll was expected. ** Resulted in significant snagging on and damage to bridge rail posts. *** The analysis showed that the barrier contained and redirected the 10,000S vehicle, but with significant damage to the transition and bridge rail elements.

† NETC 3-bar with HSS 5x4x5/16 lower rail ‡ NETC 4-bar with W8x28 posts § 3-bar AGT with original components §§ 3-bar AGT with HSS5x4x5/16 lower rail Ⱡ 3-bar AGT with 2-inch splice gap and top of posts tapered

Vehicle Stability Overall Result

Contain OCI

System Type System MASH Test No. Impact Conditions RESULTS

Speed Angle CIP Structural Adequacy

Occupant Risk Metrics 4-Bar (Concrete

Butress)

NETC 2-Bar NETC 3-Bar Bridge Rail AGT 2-Bar

(Tube Rails)

3-Bar

(Tube Rails)

NETC 4-Bar 3-Bar

(Tube Rails) w/ 5.5-ft Post Space

Slide 65

Acknowledgements

The following are the members of the Technical Committee that developed the scope of work for the project and provided technical oversight throughout the course of the research:

• Project Manager – Kirsten Seeber, CTC & Associates
• Chair – Jeff Folsom, Maine DOT
• Dale Peabody, Maine DOT
• David Kilpatrick, Connecticut DOT
• Alex Bardow, Massachusetts DOT
• Robert Landry, New Hampshire DOT
• Michael Savella, Rhode Island DOT
• Jim Lacroix, Vermont Agency of Transportation